Spherical annular seal member and method of manufacturing the same

ABSTRACT

A spherical annular seal member ( 1 ) has a seal body ( 4 ) in which a heat-resistant material ( 2 ) and a reinforcing member ( 3 ) made of a metal wire have been compressed to fill meshes of the metal wire net of the reinforcing member ( 3 ) with the heat-resistant material ( 2 ) such that the heat-resistant material ( 2 ) and the reinforcing member ( 3 ) are integrally formed in mixed form. The seal body ( 4 ) has a cylindrical inner peripheral surface ( 6 ) defining a through hole ( 5 ); an outer peripheral surface ( 10 ) constituted by a partially convex spherical surface ( 7 ); and annular end faces ( 8, 9 ) respectively provided on a large-diameter side and a small-diameter side of the partially convex spherical surface ( 7 ). In the seal body ( 4 ), the reinforcing member ( 3 ) and the heat-resistant material ( 2 ) are respectively contained at a rate of 15 to 80 wt. % and at a rate of 20 to 85 wt. %. The heat-resistant material ( 2 ) in the seal body ( 4 ) has a density of 1.20 g/cm 3  to 2.00 g/cm 3 .

This application is the US national phase of International ApplicationNo. PCT/JP02/09556 filed 18 Sep. 2002, which designated the US.PCT/JP02/09556 claims priority to JP Application No. 2001-289516 filed21 Sep. 2001. The entire contents of these applications are incorporatedherein by reference.

TECHNICAL FIELD

The present invention relates to a spherical annular seal member used ina spherical pipe joint for an automobile exhaust pipe, as well as amethod of manufacturing the same.

BACKGROUND ART

Various spherical annular seal members used in spherical pipe joints forautomobile exhaust pipes have been disclosed in, for example,JP-A-54-76759, JP-A-6-123362, JP-A-10-9396, JP-A-10-9397, and the like.

As compared with a bellows-type joint, each of the proposed sphericalannular seal members is capable of reducing the manufacturing cost andexcels in durability. However, each of these spherical annular sealmembers is formed such that a heat-resistant material formed of expandedgraphite and the like and a reinforcing member made from a metal wirenet are compressed to fill meshes of the metal wire net of thereinforcing member with the heat-resistant material such that theheat-resistant material and the reinforcing member are integrally formedin mixed form. Therefore, in addition to the problem of leakage ofexhaust gases through the spherical annular seal member itself due tosuch as the proportion of the reinforcing member to the heat-resistantmaterial and the degree of compression of the heat-resistant materialand the reinforcing member, there is an inherent problem in thatabnormal noise can occur due to the presence of the heat-resistantmaterial at the partially convex spherical surface which slidably abutsagainst a mating member. For example, if the proportion of thereinforcing member to the heat-resistant material is excessively large,or the degree of pressurization of the heat-resistant material is low,the degree of sealing by the heat-resistant material with respect toinfinitesimal passages occurring around the reinforcing member declines,resulting in initial leakage. Moreover, there is a possibility of earlyleakage of exhaust gases due to such as the oxidation and wear of theheat-resistant material at high temperatures. In addition, if theheat-resistant material at the partially convex spherical surface hasbeen pressurized to a high degree, or the proportion of exposure of theheat-resistant material with respect to the reinforcing member at thepartially convex spherical surface is extremely large, stick-slip canresult, possibly causing the occurrence of abnormal noise.

The present invention has been devised in view of the above-describedaspects, and its object is to provide a spherical annular seal memberwhich makes it possible to eliminate the leakage of exhaust gasesthrough the spherical annular seal member itself, and which makes itpossible to eliminate the occurrence of abnormal noise and has a stablesealing characteristic, as well as a method of manufacturing the same.

DISCLOSURE OF THE INVENTION

A spherical annular seal member according to a first aspect of theinvention comprises: a seal body which has an annular sliding surfaceand in which at least a heat-resistant material and a reinforcing membermade of a metal wire have been compressed to fill meshes of the metalwire net of the reinforcing member with the heat-resistant material suchthat the heat-resistant material and the reinforcing member areintegrally formed in mixed form, wherein the reinforcing member and theheat-resistant material are respectively contained at a rate of 15 to 80wt. % and at a rate of 20 to 85 wt. %, and the heat-resistant materialin the seal body has a density of 1.20 g/cm³ to 2.00 g/cm³.

In the seal body in which a heat-resistant material and a reinforcingmember made from a compressed metal wire are integrally formed in mixedform, if the reinforcing member is contained at a rate of more than 80wt. %, and the heat-resistant material is contained at a rate of lessthan 20 wt. %, sealing (filling) by the heat-resistant material withrespect to a multiplicity of infinitesimal passages (gaps) occurringaround the reinforcing member fails to be effected completely in manycases. Consequently, initial leakage of exhaust gases can result. Evenif the sealing with respect to the infinitesimal passages has beencompletely effected throughout, such sealing disappears at an earlyperiod due to such as the oxidation and wear of the heat-resistantmaterial at high temperatures, and the leakage of exhaust gases occursat an early period. On the other hand, if the reinforcing member iscontained at a rate of less than 15 wt. %, and the heat-resistantmaterial is contained at a rate of more than 85 wt. %, the amount ofreinforcing member becomes extremely small at the annular slidingsurface and in the vicinities of the annular sliding surface.Consequently, reinforcement for the heat-resistant material at theannular sliding surface and in the vicinities of the annular slidingsurface fails to be effected satisfactorily. Hence, the exfoliation ofthe heat-resistant material occurs noticeably, and it becomes difficultto expect a reinforcement effect derived from the reinforcing member.

In addition, in the above-described seal body, if the seal body is notstrongly compressed at the manufacturing stage, and the heat-resistantmaterial has a density smaller than 1.20 g/cm³, infinitesimal cavitiesoccur and spread extensively in such a heat-resistant material over longperiods of use. As a result, the leakage of exhaust gases occurs. On theother hand, if the seal body is compressed very strongly at themanufacturing stage, and the heat-resistant material has a densitygreater than 2.00 g/cm³, appropriate transfer of the heat-resistantmaterial to a mating member practically does not take place, so that thedifference between the coefficient of dynamic friction and thecoefficient of static friction becomes extremely large. Consequently,abnormal noise is likely to occur during sliding.

From the above-described perspective, the spherical annular seal memberaccording to the first aspect is free of leakage of exhaust gasesthrough the seal body itself, does not generate abnormal noise duringsliding with the mating member, and has a stable sealing characteristic.

A spherical annular seal member according to a second aspect of theinvention comprises: a seal body which has an annular sliding surfaceand in which at least a heat-resistant material and a reinforcing membermade of a metal wire have been compressed to fill meshes of the metalwire net of the reinforcing member with the heat-resistant material suchthat the heat-resistant material and the reinforcing member areintegrally formed in mixed form; and a covering layer formed integrallywith an outer peripheral surface of the seal body and formed of at leasta lubricating material, the annular sliding surface being formed by anexposed surface of the covering layer, wherein, in the seal body and thecovering layer, the reinforcing member is contained at a rate of 15 to80 wt. %, and the heat-resistant material and the lubricating materialare contained at a rate of 20 to 85 wt. %, and wherein theheat-resistant material and the lubricating material in the seal bodyand the covering layer have a density of 1.20 g/cm³ to 2.00 g/cm³.

Since the spherical annular seal member according to the second aspecthas an annular sliding surface formed by an exposed surface of thecovering layer, it is possible to ensure smoother sliding on the matingmember abutting against such an annular sliding surface. Moreover, inthe same way as the spherical annular seal member according to the firstaspect, the leakage of exhaust gases through the seal body itself doesnot occur, and abnormal noise does not occur during sliding on themating member.

A spherical annular seal member according to a third aspect of theinvention comprises: a seal body which has an annular sliding surfaceand in which at least a heat-resistant material and a reinforcing membermade of a metal wire have been compressed to fill meshes of the metalwire net of the reinforcing member with the heat-resistant material suchthat the heat-resistant material and the reinforcing member areintegrally formed in mixed form; and a covering layer formed integrallywith an outer peripheral surface of the seal body and formed such thatat least a heat-resistant material and a reinforcing member made of ametal wire have been compressed to fill meshes of the metal wire net ofthe reinforcing member with the lubricating material and theheat-resistant material such that the lubricating material, theheat-resistant material, and the reinforcing member are integrallyformed in mixed form, the annular sliding surface being formed by anexposed surface of the covering layer in which a surface constituted bythe reinforcing member and a surface constituted by the lubricatingmaterial are present in mixed form, wherein, in the seal body and thecovering layer, the reinforcing member is contained at a rate of 15 to80 wt. %, and the heat-resistant material and the lubricating materialare contained at a rate of 20 to 85 wt. %, and wherein theheat-resistant material and the lubricating material in the seal bodyand the covering layer have a density of 1.20 g/cm³ to 2.00 g/cm³.

Since the spherical annular seal member according to the third aspecthas an annular sliding surface formed by an exposed surface of thecovering layer in which a surface constituted by the reinforcing memberand a surface constituted by the lubricating material are present inmixed form, in the same way as the spherical annular seal memberaccording to the second aspect, it is possible to ensure smoothersliding on the mating member abutting against the annular slidingsurface. Moreover, the surface constituted by the lubricating materialat the exposed surface can be held by the surface constituted by thereinforcing member. In addition, the transfer of the lubricatingmaterial from the annular sliding surface to the mating member and thescraping of the lubricating material transferred to the mating membercan be effected appropriately, with the result that it is possible toensure smooth sliding over long periods of time. Furthermore, in thesame way as the spherical annular seal member according to the firstaspect, the leakage of exhaust gases through the seal body itself doesnot occur, and abnormal noise does not occur during sliding on themating member.

A spherical annular seal member according to a fourth aspect of theinvention comprises: a seal body which has an annular sliding surfaceand in which at least a heat-resistant material and a reinforcing membermade of a metal wire have been compressed to fill meshes of the metalwire net of the reinforcing member with the heat-resistant material suchthat the heat-resistant material and the reinforcing member areintegrally formed in mixed form; and a covering layer formed integrallywith an outer peripheral surface of the seal body and formed such thatat least a lubricating material, a heat-resistant material and areinforcing member made of a metal wire have been compressed to fillmeshes of the metal wire net of the reinforcing member with thelubricating material and the heat-resistant material such that thelubricating material, the heat-resistant material, and the reinforcingmember are integrally formed in mixed form, the annular sliding surfacebeing formed by an exposed surface of the covering layer in which asurface constituted by the reinforcing member and a surface constitutedby the lubricating material are present in mixed form, wherein, in anannular surface layer portion of the spherical annular seal member witha thickness of 1 mm from the annular sliding surface, the reinforcingmember is contained at a rate of 60 to 75 wt. %, the heat-resistantmaterial and the lubricating material are contained at a rate of 25 to40 wt. %, and the reinforcing member, the heat-resistant material, andthe lubricating material in the annular surface layer portion have adensity of 3.00 g/cm³ to 5.00 g/cm³, and wherein, in a remaining annularportion of the spherical annular seal member excluding the annularsurface layer portion, the reinforcing member is contained at a rate of20 to 70 wt. %, and the heat-resistant material is contained at a rateof 30 to 80 wt. %.

In the spherical annular seal member, the thickness of the coveringlayer in which the lubricating material, the heat-resistant material,and the reinforcing member are integrally formed in mixed form isexperientially sufficient if it is 1 mm or less from the standpoint ofits service life attributable to wear. Accordingly, if the reinforcingmember is contained at a rate of less than 60 wt. % in the annularsurface layer portion of the spherical annular seal member with athickness of 1 mm from the annular sliding surface, and theheat-resistant material and the lubricating material are containedtherein at a rate of more than 40 wt. %, it becomes difficult tosufficiently obtain the effect of the reinforcing member at that surfacelayer portion. Consequently, the exfoliation and coming off at thatsurface layer portion are likely to occur. On the other hand, if thereinforcing member is contained at a rate of more than 75 wt. %, and theheat-resistant material and the lubricating material are contained at arate of less than 25 wt. %, sealing (filling) by the heat-resistantmaterial with respect to the multiplicity of infinitesimal passages(gaps) occurring around the reinforcing member fails to be effectedcompletely. Consequently, initial leakage of exhaust gases through thesurface layer portion can result. Even if the sealing with respect tothe infinitesimal passages has been completely effected throughout, suchsealing disappears at an early period due to such as the oxidation andwear of the heat-resistant material at high temperatures, and theleakage of exhaust gases occurs at an early period.

In addition, if the reinforcing member, the heat-resistant material, andthe lubricating material in the annular surface layer portion have adensity smaller than 3.00 g/cm³, it means that the seal body has notbeen strongly compressed at the manufacturing stage. As such,infinitesimal cavities occur and spread extensively in such an annularsurface layer portion over long periods of use. As a result, the leakageof exhaust gases occurs. On the other hand, if the reinforcing member,the heat-resistant material, and the lubricating material have a densitygreater than 5.00 g/cm³,it means that the seal body has been compressedvery strongly at the manufacturing stage. As such, appropriate transferof the heat-resistant material to a mating member practically does nottake place, so that the difference between the coefficient of dynamicfriction and the coefficient of static friction becomes extremely large.Consequently, abnormal noise is likely to occur during sliding.

Furthermore, if the reinforcing member is contained at a rate of lessthan 20 wt. %.in the remaining annular portion of the spherical annularseal member excluding the annular surface layer portion, and theheat-resistant material is contained therein at a rate of more than 80wt. %, reinforcement for the heat-resistant material at the remainingannular portion fails to be effected satisfactorily. Hence, theexfoliation of the heat-resistant material occurs noticeably, and itbecomes difficult to expect the reinforcement effect derived from thereinforcing member. On the other hand, if the reinforcing member iscontained at a rate of more than 70 wt. %, and the heat-resistantmaterial is contained at a rate of less than 30 wt. %, sealing (filling)by the heat-resistant material with respect to a multiplicity ofinfinitesimal passages (gaps) occurring around the reinforcing memberfails to be effected completely in many cases. Consequently, initialleakage of exhaust gases can result. Even if the sealing with respect tothe infinitesimal passages has been completely effected throughout, suchsealing disappears at an early period due to such as the oxidation andwear of the heat-resistant material at high temperatures, and theleakage of exhaust gases occurs at an early period.

Hence, in accordance with the spherical annular seal member according tothe fourth aspect, in the annular surface layer portion, the reinforcingmember is contained at a rate of 60 to 75 wt. %, the heat-resistantmaterial and the lubricating material are contained at a rate of 25 to40 wt. %, and the reinforcing member, the heat-resistant material, andthe lubricating material in the annular surface layer portion have adensity of 3.00 g/cm³ to 5.00 g/cm³. Therefore, the exfoliation andcoming off of the surface layer portion are difficult to occur, andinitial leakage of exhaust gases through the surface layer portion doesnot occur. Moreover, the leakage of exhaust gases can be prevented notonly in an early period but in a longer period, and the occurrence ofabnormal noise can be prevented during sliding on the mating member.

In addition, in accordance with the spherical annular seal memberaccording to the fourth aspect, in a remaining annular portion of thespherical annular seal member excluding the annular surface layerportion, the reinforcing member is contained at a rate of 20 to 70 wt.%, and the heat-resistant material is contained at a rate of 30 to 80wt. %. Therefore, the leakage of exhaust gases through the remainingannular portion can be prevented reliably, and reinforcement of theheat-resistant material in this portion is rendered satisfactory,satisfactorily preventing the exfoliation of the heat-resistantmaterial.

A spherical annular seal member according to a fifth aspect of theinvention comprises: a seal body which has an annular sliding surfaceand in which at least a heat-resistant material and a reinforcing membermade of a metal wire have been compressed to fill meshes of the metalwire net of the reinforcing member with the heat-resistant material suchthat the heat-resistant material and the reinforcing member areintegrally formed in mixed form; and a covering layer formed integrallywith an outer peripheral surface of the seal body and formed such thatat least a lubricating material, a heat-resistant material and areinforcing member made of a metal wire have been compressed to fillmeshes of the metal wire net of the reinforcing member with thelubricating material and the heat-resistant material such that thelubricating material, the heat-resistant material, and the reinforcingmember are integrally formed in mixed form, the annular sliding surfacebeing formed by an exposed surface of the covering layer in which asurface constituted by the reinforcing member and a surface constitutedby the lubricating material are present in mixed form, wherein, in thecovering layer, the reinforcing member is contained at a rate of 60 to75 wt. %, and the heat-resistant material and the lubricating materialare contained at a rate of 25 to 40 wt. %.

In accordance with the spherical annular seal member according to thefifth aspect, in the same way as the spherical annular seal memberaccording to the fourth aspect, the reinforcing member is contained inthe covering layer at a rate of 60 to 75 wt. %, and the heat-resistantmaterial and the lubricating material are contained therein at a rate of25 to 40 wt. %. Therefore, the exfoliation and coming off of thecovering layer are difficult to occur, and initial and early leakage ofexhaust gases through the covering layer can be prevented reliably.

A spherical annular seal member according to a fifth aspect of theinvention comprises: a seal body which has an annular sliding surfaceand in which at least a heat-resistant material and a reinforcing membermade of a metal wire have been compressed to fill meshes of the metalwire net of the reinforcing member with the heat-resistant material suchthat the heat-resistant material and the reinforcing member areintegrally formed in mixed form; and a covering layer formed integrallywith an outer peripheral surface of the seal body and formed such thatat least a lubricating material, a heat-resistant material and areinforcing member made of a metal wire have been compressed to fillmeshes of the metal wire net of the reinforcing member with thelubricating material and the heat-resistant material such that thelubricating material, the heat-resistant material, and the reinforcingmember are integrally formed in mixed form, the annular sliding surfacebeing formed by an exposed surface of the covering layer in which asurface constituted by the reinforcing member and a surface constitutedby the lubricating material are present in mixed form, wherein, in theannular sliding surface, the surface constituted by the reinforcingmember is exposed at an area rate of 0.5 to 30%, and the surfaceconstituted by the lubricating material is exposed at an area rate of 70to 99.5%.

If, in the annular sliding surface, the surface constituted by thereinforcing member is exposed at an area rate of less than 0.5%, and thesurface constituted by the lubricating material is exposed at an arearate of more than 99.5%, the annular sliding surface is substantiallyoccupied by the surface constituted by the lubricating material, so thatthe exfoliation and coming off of the surface constituted by thelubricating material are likely to occur. Further, despite the fact thatthe transfer of the lubricating material from the annular slidingsurface to the mating member takes place more than necessary, thescraping of the lubricating material transferred to the mating member isnot effected as much. On the other hand, if the surface constituted bythe reinforcing member is exposed at an area rate of more than 30%, andthe surface constituted by the lubricating material is exposed at anarea rate of less than 70%, the effect derived from the lubricatingmaterial becomes small. Hence, the wear of the mating member whichslidably abuts against the annular sliding surface and relatively slidesbecomes noticeable, and it becomes impossible to obtain smooth slidingover long periods of use.

Therefore, in accordance with the spherical annular seal memberaccording to the sixth embodiment, it is possible to prevent theexfoliation and coming off of the surface constituted by the lubricatingmaterial at the annular sliding surface. Moreover, it is possible toobtain smooth sliding on the mating member over long periods of use, andeliminate the occurrence of abnormal noise.

Although, in the spherical annular seal member according to theabove-described various aspects, the heat-resistant material preferablycontains expanded graphite as in the spherical annular seal memberaccording to a seventh aspect of the invention, the invention is notlimited to the same. For instance, in addition to or in substitution ofexpanded graphite, the heat-resistant material may contain those whichare selected from one or two or more kinds of mica and asbestos. Inaddition, in the spherical annular seal member according to theabove-described various aspects, the annular sliding surface preferablyincludes a partially convex spherical surface, a partially concavespherical surface, or a truncated conical surface as in the sphericalannular seal member in accordance with an eighth aspect of theinvention. The spherical annular seal member at such a partially convexspherical surface, partially concave spherical surface, or truncatedconical surface is adapted to slidably abut against the mating member.Furthermore, in the above-described various aspects, the sphericalannular seal member may comprise an outer peripheral surface includingthe annular sliding surface as in the spherical annular seal memberaccording to a ninth aspect of the invention, may comprise an innerperipheral surface including the annular sliding surface as in thespherical annular seal member according to a 10th aspect of theinvention.

It should be noted that the annular sliding surface of the sphericalannular seal member may be adapted to slidably abut against the matingmember wholly, or may be alternatively adapted to slidably abut againstthe mating member partially in belt form. Furthermore, the annularsliding surface is not limited to the one which includes one partiallyconvex spherical surface, one partially concave spherical surface, orone truncated conical surface, but may include two or more partiallyconvex spherical surfaces or partially concave spherical surfaces havingdifferent positions of the center of curvature or radii of curvature, ortruncated conical surfaces having different degrees of inclination.

A method of the invention for manufacturing the spherical annular sealmember according to any one of the above-described aspects comprises thesteps of: preparing a heat-resistant sheet member containing theheat-resistant material and a reinforcing sheet member made from themetal wire net; forming a tubular base member by superposing thereinforcing member on the heat-resistant sheet member and bysubsequently convoluting a superposed assembly thereof into acylindrical form; and fitting the tubular base member over an outerperipheral surface of a core of a die, and compression-forming thetubular base member in the die in an axial direction of the core.

In addition, a method of the invention for manufacturing the sphericalannular seal member according to any one of the above-described first toninth aspects comprises the steps of: forming a tubular base member bysuperposing a reinforcing sheet member containing the heat-resistantmaterial on a heat-resistant sheet member made from the metal wire netand by subsequently convoluting a superposed assembly thereof into acylindrical form; forming a cylindrical preform by winding acovering-layer forming member, which is constituted by anotherheat-resistant sheet member containing the heat-resistant material, alubricating layer containing the lubricating material and coated on onesurface of the other heat-resistant sheet member, and anotherreinforcing sheet member disposed in the lubricating layer and made fromthe metal wire net, around an outer peripheral surface of the tubularbase member with a surface of the lubricating layer placed on an outerside; and fitting the cylindrical preform over an outer peripheralsurface of a core of a die, and compression-forming the cylindricalpreform in the die in an axial direction of the core.

Further, a method of the invention for manufacturing the sphericalannular seal member according to any one of the above-described first toeighth and tenth aspects comprises the steps of: forming a tubular basemember by convoluting a covering-layer forming member, which isconstituted by a heat-resistant sheet member, a lubricating layercontaining the lubricating material and coated on one surface of theheat-resistant sheet member, and a reinforcing sheet member disposed inthe lubricating layer and made from the metal wire net, with a surfaceof the lubricating layer placed on an inner side; forming a cylindricalpreform by superposing another reinforcing sheet member made from themetal wire net on another heat-resistant sheet member containing theheat-resistant material and by subsequently winding a superposedassembly thereof around an outer peripheral surface of the tubular basemember; and fitting the cylindrical preform over an outer peripheralsurface of a core of a die, and compression-forming the cylindricalpreform in the die in an axial direction of the core.

According to the invention, it is possible to provide a sphericalannular seal member which makes it possible to eliminate the leakage ofexhaust gases through the spherical annular seal member itself, andwhich makes it possible to eliminate the occurrence of abnormal noise,as well as a method of manufacturing the same.

Hereafter, a description will be given of the present invention and amode for carrying it out on the basis of preferred embodimentsillustrated in the drawings. It should be noted that the invention isnot limited to these embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical cross sectional view illustrating an embodiment ofa spherical annular seal member in accordance with the presentinvention;

FIG. 2 is a perspective view of a heat-resistant sheet member in amanufacturing process of the embodiment shown in FIG. 1;

FIG. 3 is a diagram explaining a method of forming a reinforcing sheetmember made from a metal wire net in the manufacturing process of theembodiment shown in FIG. 1;

FIG. 4 is a plan view of a tubular base member in the manufacturingprocess of the embodiment shown in FIG. 1;

FIG. 5 is a vertical cross-sectional view illustrating a state in whichthe tubular base member is inserted in a die in the manufacturingprocess of the embodiment shown in FIG. 1;

FIG. 6 is a vertical cross-sectional view of an exhaust pipe sphericaljoint in which the spherical annular seal member in accordance with theembodiment shown in FIG. 1 has been incorporated;

FIG. 7 is a vertical cross-sectional view illustrating anotherembodiment of the spherical annular seal member in accordance with theinvention;

FIG. 8 is a vertical cross-sectional view illustrating still anotherembodiment of the spherical annular seal member in accordance with theinvention;

FIG. 9 is a partially enlarged cross-sectional view of the embodimentshown in FIG. 8;

FIG. 10 is a vertical cross-sectional view of the heat-resistant sheetmember in which a lubricating layer has been formed in the manufacturingprocess of the embodiment shown in FIG. 8;

FIG. 11 is a diagram explaining the method of forming a covering-layerforming member in the manufacturing process of the embodiment shown inFIG. 8;

FIG. 12 is a diagram explaining the method of forming the covering-layerforming member in the manufacturing process of the embodiment shown inFIG. 8;

FIG. 13 is a plan view explaining the method of forming a cylindricalpreform in the manufacturing process of the embodiment shown in FIG. 8;

FIG. 14 is a vertical cross-sectional view illustrating a furtherembodiment of the spherical annular seal member in accordance with theinvention;

FIG. 15 is a vertical cross-sectional view of the exhaust pipe sphericaljoint in which the spherical annular seal member in accordance with theembodiment shown in FIG. 14 has been incorporated;

FIG. 16 is a vertical cross-sectional view illustrating a state in whichthe tubular base member is inserted in a die in the manufacturingprocess of the embodiment shown in FIG. 14;

FIG. 17 is a vertical cross-sectional view illustrating a state ofcompression forming in the manufacturing process of the embodiment shownin FIG. 14;

FIG. 18 is a vertical cross-sectional view of the exhaust pipe sphericaljoint in which the spherical annular seal member in accordance with astill further embodiment has been incorporated; and

FIG. 19 is a vertical cross-sectional view of the exhaust pipe sphericaljoint in which the spherical annular seal member in accordance with afurther embodiment has been incorporated.

EMBODIMENTS

In FIG. 1, a spherical annular seal member 1 has a seal body 4 in whicha heat-resistant material 2 and a reinforcing member 3 made of a metalwire have been compressed to fill meshes of the metal wire net of thereinforcing member 3 with the heat-resistant material 2 such that theheat-resistant material 2 and the reinforcing member 3 are integrallyformed in mixed form. In this embodiment, the seal body 4 itself has acylindrical inner peripheral surface 6 defining a through hole 5; anouter peripheral surface 10 including a partially convex sphericalsurface 7 serving as an annular sliding surface, i.e., in thisembodiment the outer peripheral surface 10 constituted by only thepartially convex spherical surface 7; and annular end faces 8 and 9respectively provided on a large-diameter side and a small-diameter sideof the partially convex spherical surface 7. In such a seal body 4, thereinforcing member 3 and the heat-resistant material 2 are respectivelycontained at a rate of 15 to 80 wt. % and at a rate of 20 to 85 wt. %.The heat-resistant material 2 in the seal body 4 has a density of 1.20g/cm³ to 2.00 g/cm³.

The heat-resistant material 2 containing expanded graphite is formed bypressurizing and compressing an expanded graphite sheet serving as aheat-resistant sheet member and obtained by compacting expanded graphiteparticles. The heat-resistant material 2 may contain such as phosphoruspentoxide, phosphate, and other oxidation inhibitors or the like, asrequired.

The reinforcing member 3 is formed by pressurizing and compressing ametal wire net whose meshes are 3 to 6 mm or thereabouts and which isformed by weaving or knitting by using one or more fine wire membershaving a diameter of 0.10 to 0.32 mm or thereabouts. The fine wiresinclude, as an iron-based wire, a stainless steel wire made of such asaustenitic stainless steels SUS 304 or SUS 316, a ferritic stainlesssteel SUS 430, or an iron wire (JIS-G-3532) or a galvanized iron wire(JIS-G-3547), or, as a copper wire, a wire member made of acopper-nickel alloy (cupro-nickel), a copper-nickel-zinc alloy (nickelsilver), brass, or beryllium copper.

As the reinforcing member 3, in addition to the above-described metalwire net, it is also possible to use as the metal wire net a so-calledexpanded metal in which a stainless steel sheet or a phosphor bronzesheet with a thickness of 0.3 to 0.5 mm or thereabouts is slotted andthe slots are expanded to form rows of regular meshes of 3 to 6 mm.

Next, a description will be given of a method of manufacturing thespherical annular seal member 1 shown in FIG. 1. First, a strip-likeheat-resistant sheet member 11 and a reinforcing sheet member 16 areprepared. The heat-resistant sheet member 11 is composed of expandedgraphite as the heat-resistant material 2 and cut to a predeterminedwidth and length, such as the one shown in FIG. 2. The reinforcing sheetmember 16 is formed such that a metal wire net formed by weaving orknitting fine metal wires is cut into a predetermined width(substantially identical to the width of the heat-resistant sheetmember) and a predetermined length. Alternatively, as shown in FIG. 3,after a cylindrical metal wire net 12 is formed by knitting fine metalwires, this cylindrical metal wire net 12 is passed between a pair ofrollers 13 and 14 so as to fabricate a belt-shaped metal wire net 15 ofa predetermined width (substantially identical to the width of theheat-resistant sheet member), and this belt-shaped metal wire net 15 iscut to a predetermined length. Next, the heat-resistant sheet member 11and the reinforcing sheet member 16 are superposed one on top of theother, and this superposed assembly is convoluted with theheat-resistant sheet member 11 placed on the inner side such thatheat-resistant sheet member 11 is convoluted with one more turn, therebyforming a tubular base member 17, as shown in FIG. 4. Further, a die 27such as the one shown in FIG. 5 is prepared. The die 27 has acylindrical inner wall surface 21, a partially concave spherical innerwall surface 22 continuing from the cylindrical inner wall surface 21,and a through hole 23 continuing from the partially concave sphericalinner wall surface 22. As a stepped core 24 is inserted in the throughhole 23, a hollow cylindrical portion 25 and a spherical annular hollowportion 26 continuing from the hollow cylindrical portion 25 are formedinside the die 27. Then, the tubular base member 17 is fitted over thestepped core 24 of the die 27. The tubular base member 17 located in thehollow cylindrical portion 25 and the spherical annular hollow portion26 of the die 27 is subjected to compression forming with apredetermined pressure in the direction of the core axis, therebyforming the spherical annular seal member 1 made up of the seal body 4having the partially convex spherical surface 7, as shown in FIG. 1.

Then, by appropriately selecting the thickness of the heat-resistantsheet member 11 used as the heat-resistant material 2, the kind, wirediameter, and the degree of mesh of the wire of the metal wire net usedas the reinforcing member 3, the degree of pressure with respect to thetubular base member 17, and the like, it is possible to obtain thespherical annular seal member 1 made up of the seal body 4 in which thereinforcing member 3 and the heat-resistant material 2 are respectivelycontained at a rate of 15 to 80 wt. % and at a rate of 20 to 85 wt. %.The heat-resistant material 2 in the seal body 4 has a density of 1.20g/cm³ to 2.00 g/cm³.

The spherical annular seal member 1 is used by being incorporated in anexhaust pipe spherical joint 31 shown in FIG. 6, for example. That is, aflange 34 is secured by such as welding to an outer peripheral surfaceof an upstream-side exhaust pipe 32, which is connected to an engine, byleaving a pipe end 33. The spherical annular seal member 1 is fittedover the pipe end 33 at the inner peripheral surface 6 defining thethrough hole 5, and is seated with its large-diameter-side end face 8abutting against that flange 34. A downstream-side exhaust pipe 44opposes the upstream-side exhaust pipe 32 and is connected to a muffler.A flared portion 43, which serves as a mating member and is comprised ofa concave spherical surface portion 41 and a flange portion 42 providedat a rim of an opening portion of the concave spherical surface portion41, is formed integrally on the downstream-side exhaust pipe 44. Thedownstream-side exhaust pipe 44 is disposed with the concave sphericalsurface portion 41 slidably abutting against the partially convexspherical surface 7 of the spherical annular seal member 1.

In the exhaust pipe spherical joint 31 shown in FIG. 6, thedownstream-side exhaust pipe 44 is constantly urged resiliently towardthe upstream-side exhaust pipe 32 by means of a pair of bolts 51 eachhaving one end fixed to the flange 34 and another end arranged by beinginserted in the flange portion 42 of the flared portion 43, and by meansof a pair of coil springs 52 each arranged between an enlarged head ofthe bolt 51 and the flange portion 42. The exhaust pipe spherical joint31 is arranged such that relative angular displacements occurring in theupstream- and downstream-side exhaust pipes 32 and 44 are allowed bysliding between the partially convex spherical surface 7 of thespherical annular seal member 1 and the concave spherical surfaceportion 41 of the flared portion 43 formed at the end of thedownstream-side exhaust pipe 44.

The spherical annular seal member 1 which is applied to such an exhaustpipe spherical joint 31 is made up of the seal body 4 in which thereinforcing member 3 and the heat-resistant material 2 are respectivelycontained at a rate of 15 to 80 wt. % and at a rate of 20 to 85 wt. %,and the heat-resistant material 2 has a density of 1.20 g/cm³ to 2.00g/cm³. Therefore, the leakage of exhaust gases through the seal body 4itself does not occur, and abnormal noise does not occur during slidingon the concave spherical surface portion 41 which is the mating member.

Although the spherical annular seal member 1, in the above description,is formed by the seal body 4, the spherical annular seal member 1 may beformed by the seal body and a covering layer, as shown in FIG. 7.Namely, a spherical annular seal member 61 shown in FIG. 7 has an outerperipheral surface 60 including a partially convex spherical surface 62serving as an annular sliding surface, i.e., in this embodiment theouter peripheral surface 60 constituted by only the partially convexspherical surface 62. The spherical annular seal member 61 further hasthe aforementioned seal body 4 and a covering layer 63 formed of alubricating material and formed integrally with the outer peripheralsurface 7 (the aforementioned partially convex spherical surface 7) ofthe seal body 4, the partially convex spherical surface 62 being formedby the exposed surface of the covering layer 63.

As for the covering layer 63, the lubricating material is applied to theouter peripheral surface 7 of the seal body 4 formed in the same way asdescribed above, by brushing, immersion, spraying, or the like to assumea thickness of 10 to 300 μm or thereabouts. After the lubricatingmaterial thus applied is dried, the exposed surface is smoothed, and thecovering layer 63 is formed by the partially convex spherical surface 62constituted by such a smooth exposed surface.

The lubricating material as a material for forming the covering layer 63is polytetrafluoroethylene resin, a material whose principal componentis polytetrafluoroethylene resin and which contains boron nitride, asrequired, or the like, and the covering layer 64 is formed by applyingan aqueous dispersion thereof.

The spherical annular seal member 61 shown in FIG. 7 has on the outerperipheral surface 7 of the seal body 4 the covering layer 63constituted by the lubricating material, and has the partially convexspherical surface 62 formed by the exposed surface of the covering layer63. Therefore, in the application to the exhaust pipe spherical joint,it is possible to ensure smoother sliding on the mating member abuttingagainst such a partially convex spherical surface 62. Moreover, in thesame way as the spherical annular seal member 1, the leakage of exhaustgases through the seal body 4 itself does not occur, and abnormal noisedoes not occur during sliding on the concave spherical surface portion41 which is the mating member.

The spherical annular seal member in accordance with the invention maybe a spherical annular seal member 71 such as the one shown in FIGS. 8and 9, instead of the spherical annular seal members 1 and 61 shown inFIGS. 1 and 7. The spherical annular seal member 71 shown in FIGS. 8 and9 has an outer peripheral surface 70 including a partially convexspherical surface 72 serving as the annular sliding surface, i.e., inthis embodiment the outer peripheral surface 70 constituted by only thepartially convex spherical surface 72. The spherical annular seal member71 further has the seal body 4 as well as a covering layer 77 which isformed integrally with an outer peripheral surface 73 (corresponding tothe aforementioned partially convex spherical surface 7 but having anirregular surface) of the seal body 4, and in which a lubricatingmaterial 74, a heat-resistant material 75, and a reinforcing member 76made from a metal wire net have been compressed to fill the meshes ofthe metal wire net of the reinforcing member 76 with the lubricatingmaterial 74 and the heat-resistant material 75, such that thelubricating material 74, the heat-resistant material 75, and thereinforcing member 76 are integrated in mixed form. The partially convexspherical surface 72 is formed by the exposed surface of the coveringlayer 77 in which a surface 78 constituted by the reinforcing member 76and a surface 79 constituted by the lubricating material 74 are presentin mixed form. In the seal body 4 and the covering layer 77, thereinforcing members 3 and 76 are contained at a rate of 15 to 80 wt. %,and the heat-resistant materials 2 and 75 and the lubricating material74 are contained at a rate of 20 to 85 wt. %. The heat-resistantmaterials 2 and 75 and the lubricating material 74 in the seal body 4and the covering layer 77 have a density of 1.20 g/cm³ to 2.00 g/cm³.

Next, a description will be given of the method of manufacturing thespherical annular seal member 71 shown in FIGS. 8 and 9. First, thetubular base member 17 such as the one shown in FIG. 4 is prepared inthe same way as the spherical annular seal member 1. Next, theheat-resistant sheet member 11 such as the one shown in FIG. 2 isprepared separately. An aqueous dispersion containingpolytetrafluoroethylene resin as the lubricating material is coated onone surface of this other heat-resistant sheet member 11 by means ofbrushing, roller coating, spraying, or the like. This coating is thendried to form a lubricating layer 80 such as the one shown in FIG. 10.Further, a reinforcing sheet member 81 made from the belt-shaped metalwire net 15 such as the one shown in FIG. 3 is prepared separately.Subsequently, as shown in FIG. 11, the heat-resistant sheet member 11having the lubricating layer 80 is inserted into the reinforcing sheetmember 81, and, as shown in FIG. 12, an assembly thereof is passedbetween a pair of rollers 82 and 83 so as to be formed integrally. Thus,a covering-layer forming member 84 is formed which is constituted of theother heat-resistant sheet member 11, the lubricating layer 80containing the lubricating material coated on one surface of that otherheat-resistant sheet member 11, and the other reinforcing sheet member81 made from the metal wire net 12 disposed in the lubricating layer 80.The covering-layer forming member 84 thus obtained is wound around theouter peripheral surface of the tubular base member 17 with thelubricating layer 80 placed on the outer side, thereby fabricating acylindrical preform 85, as shown in FIG. 13. This cylindrical preform 85is placed in the die 27 and is subjected to compression forming in thesame way as described above, thereby obtaining the spherical annularseal member 71.

Then, by appropriately selecting the thickness of the heat-resistantsheet members 11 used as the heat-resistant materials 2 and 75, thekind, wire diameter, and the degree of mesh of the wire of the metalwire nets 12 used as the reinforcing members 3 and 76, the thickness ofthe lubricating layer 80, the degree of pressure with respect to thecylindrical preform 85, and the like, it is possible to obtain thespherical annular seal member 71 which has the seal body 4 and thecovering layer 77 and in which, in the seal body 4 and the coveringlayer 77, the reinforcing members 3 and 76 are contained at a rate of 15to 80 wt. %, and the heat-resistant materials 2 and 75 and thelubricating material 74 are contained at a rate of 20 to 85 wt. %, andin which the heat-resistant materials 2 and 75 and the lubricatingmaterial 74 in the seal body 4 and the covering layer 77 have a densityof 1.20 g/cm³ to 2.00 g/cm³.

The spherical annular seal member 71 has on the outer peripheral surface73 of the seal body 4 the covering layer 77 in which the lubricatingmaterial 74, the heat-resistant material 75, and the reinforcing member76 are integrated in mixed form. Further, the spherical annular sealmember has the partially convex spherical surface 72 formed by theexposed surface of the covering layer 77 in which the surface 78constituted by the reinforcing member 76 and the surface 79 constitutedby the lubricating material 74 are present in mixed form. Therefore, inthe same way as the spherical annular seal member 61, it is possible toensure smoother sliding on the concave spherical surface portion 41which is the mating member abutting against the partially convexspherical surface 72. Moreover, the surface 79 constituted by thelubricating material 74 at the exposed surface can be held by thesurface 78 constituted by the reinforcing member 76. In addition, thetransfer of the lubricating material 74 from the partially convexspherical surface 72 to the concave spherical surface portion 41 and thescraping of the lubricating material 74 transferred to the concavespherical surface portion 41 can be effected appropriately, with theresult that it is possible to ensure smooth sliding over long periods oftime. Furthermore, in the same way as the spherical annular seal member1, the leakage of exhaust gases through the seal body 4 itself does notoccur, and abnormal noise does not occur during sliding on the concavespherical surface portion 41 which is the mating member.

Alternatively, by using a manufacturing method similar to that for thespherical annular seal member 71, and by appropriately selecting thethickness of the heat-resistant sheet members 11 used as theheat-resistant materials 2 and 75, the kind, wire diameter, and thedegree of mesh of the wire of the metal wire nets 12 used as thereinforcing members 3 and 76, the thickness of the lubricating layer 80,the degree of pressure with respect to the cylindrical preform 85, andthe like, a spherical annular seal member may be formed which has theseal body 4 and the covering layer 77 and has an annular surface layerportion 91 with a thickness of 1 mm from the partially convex sphericalsurface 62 toward the center. In this annular surface layer portion 91,the reinforcing members 3 and 76 are contained at a rate of 60 to 75 wt.%, the heat-resistant materials 2 and 75 and the lubricating material 74are contained at a rate of 25 to 40 wt. %, and the reinforcing members 3and 76, the heat-resistant materials 2 and 75, and the lubricatingmaterial 74 in that annular surface layer portion 91 have a density of3.00 g/cm³ to 5.00 g/cm³. In the remaining annular portion of thespherical annular seal member excluding the annular surface layerportion 91, the reinforcing member 3 is contained at a rate of 20 to 70wt. %, and the heat-resistant material 2 is contained at a rate of 30 to80 wt. %.

In such a spherical annular seal member, the exfoliation and coming offof the surface layer portion 91 are difficult to occur, and initialleakage of exhaust gases through the surface layer portion 91 does notoccur. Moreover, the leakage of exhaust gases can be prevented not onlyin an early period but in a longer period, and the occurrence ofabnormal noise can be prevented during sliding on the concave sphericalsurface portion 41 which is the mating member. In addition, the leakageof exhaust gases through the remaining annular portion can be preventedreliably, and reinforcement of the heat-resistant material in thisportion is rendered satisfactory, satisfactorily preventing theexfoliation of the heat-resistant material.

Still alternatively, by using a manufacturing method similar to that forthe spherical annular seal member 71, and by appropriately selecting thethickness of the other heat-resistant sheet member 11 used as theheat-resistant material 75, the kind, wire diameter, and the degree ofmesh of the wire of the metal wire net 12 used as the reinforcing member76, the thickness of the lubricating layer 80, and the like, a sphericalannular seal member may be formed which has the seal body 4 and thecovering layer 77 wherein, in the covering layer 77, the reinforcingmember 76 is contained at a rate of 60 to 75 wt. %, and the lubricatingmaterial 74 and the heat-resistant material 75 are contained at a rateof 25 to 40 wt. %. In such a spherical annular seal member, theexfoliation and coming off of the portion of the covering layer 77 aredifficult to occur, and it is possible to reliably prevent the initialand early leakage of exhaust gases through the portion of the coveringlayer 77.

In addition, by using a manufacturing method similar to that for thespherical annular seal member 71, and by appropriately selecting thethickness of the other heat-resistant sheet member 11 used as theheat-resistant material 75, the kind, wire diameter, and the degree ofmesh of the wire of the metal wire net 12 used as the reinforcing member76, the thickness of the lubricating layer 80, and the like, a sphericalannular seal member may be formed which has the seal body 4 and thecovering layer 77 wherein, in the partially convex spherical surface 72,the surface 78 constituted by the reinforcing member 76 is exposed at anarea rate of 0.5 to 30%, and the surface 79 constituted by thelubricating material 74 is exposed at an area rate of 70 to 99.5%. Insuch a spherical annular seal member, the exfoliation and coming off ofthe surface 79 constituted by the lubricating material 74 at thepartially convex spherical surface 72 can be prevented, and it ispossible to obtain smooth sliding on the concave spherical surfaceportion 41 even in long periods of use.

Incidentally, the example of the spherical annular seal member 1, 61, or71 has been described above which has the outer peripheral surface 10,60, or 70 including the partially convex spherical surface 7, 62, or 72as the annular sliding surface. Alternately, however, in the inventionit is possible to use a spherical annular seal member 101 having aninner peripheral surface 100 including the a truncated conical surface102 as the annular sliding surface, as shown in FIG. 14. In addition tothe truncated conical surface 102, the spherical annular seal member 101has the inner peripheral surface 100 including a cylindrical innersurface 103 continuing from the truncated conical surface 102; outerperipheral surfaces 106 including a truncated conical outer surface 104corresponding to the truncated conical surface 102 as well as acylindrical outer surface 105 continuing from the truncated conicalouter surface 104; annular end faces 108 and 109 respectively providedon the large-diameter side and the small-diameter side of the truncatedconical surface 102. The spherical annular seal member 101 isconstructed in a manner similar to that for the spherical annular sealmember 1, 61, or 71.

The spherical annular seal member 101 shown in FIG. 14 and having theinner peripheral surface 100 including the truncated conical surface 102as the annular sliding surface is used by being incorporated in anexhaust pipe spherical joint 131 shown in FIG. 15, for example. That is,a flange member 134 is secured by such as welding to the outerperipheral surface of the upstream-side exhaust pipe 32 connected to theengine side. The end face 109, the truncated conical outer surface 104,and the cylindrical outer surface 105 of the outer peripheral surfaces106 are respectively fitted exactly to inner peripheral surfaces 137 ofthe flange member 132, including an annular face 134, a truncatedconical surface 135, and a cylindrical surface 136 of a truncatedconical portion 133. The spherical annular seal member 101 is thusfitted at its outer peripheral surfaces 106. The downstream-side exhaustpipe 44 opposes the upstream-side exhaust pipe 32 and is connected tothe muffler side. A convex spherical surface member 140 serving as themating member integrally having a convex spherical surface portion 138and a flange portion 139 is secured to the downstream-side exhaust pipe44 by welding or the like. The downstream-side exhaust pipe 44 isdisposed with the concave spherical surface portion 138 slidablyabutting against the truncated conical surface 102 of the sphericalannular seal member 101.

In the exhaust pipe spherical joint 131 shown in FIG. 15, thedownstream-side exhaust pipe 44 is constantly urged resiliently towardthe upstream-side exhaust pipe 32 by means of the pair of bolts 51 eachhaving one end fixed to the flange portion 139 and another end arrangedby being inserted in a flange portion 141 of the flange member 132 witha sufficient gap, and by means of the pair of coil springs 52 eacharranged between the enlarged head of the bolt 51 and the flange portion141. The exhaust pipe spherical joint 131 is arranged such that relativeangular displacements occurring in the upstream- and downstream-sideexhaust pipes 32 and 44 are allowed by sliding between the truncatedconical surface 102 of the spherical annular seal member 101 and theconcave spherical surface portion 138 of the convex spherical surfacemember 140 secured to the end of the downstream-side exhaust pipe 44 bywelding or the like.

Since the spherical annular seal member 101 which is applied to such anexhaust pipe spherical joint 131 is constructed in the same way as thespherical annular seal member 1, 61, or 71, the spherical annular sealmember 101 produces effects similar to those of the above-describedspherical annular seal member 1, 61, or 71.

To manufacture the spherical annular seal member 101 shown in FIG. 14and corresponding to the spherical annular seal member 1 or 61, thestrip-like heat-resistant sheet member 11 such as the one shown in FIG.2 referred to earlier and the reinforcing sheet member 16 such as theone shown in FIG. 3 referred to earlier are first prepared. Next, theheat-resistant sheet member 11 and the reinforcing sheet member 16 aresuperposed one on top of the other, and this superposed assembly isconvoluted with the heat-resistant sheet member 11 placed on the innerside such that heat-resistant sheet member 11 is convoluted with onemore turn, thereby forming the tubular base member 17, as shown in FIG.4. Further, a die 153 such as the one shown in FIG. 16 is prepared. Thedie 153 has a cylindrical inner wall surface 145, a truncated conicalsurface 146 continuing from the cylindrical inner wall surface 145, anda circular hole 148 continuing from a truncated conical surface 146 viaa stepped portion 147. As a stepped core 149 is inserted in the throughhole 148, a hollow cylindrical portion 151 and a truncated conicalhollow portion 152 continuing from the hollow cylindrical portion 151are formed inside the die 153. The tubular base member 17 is inserted inthe hollow cylindrical portion 151, i.e., over the outer peripheralsurface of the stepped core 149 of the die 153 so as to be fitted to thecylindrical inner wall surface 145. After the fitting of the tubularbase member 17 to the cylindrical inner wall surface 145, a cylindricalpressing member 162 having a truncated conical surface 161 at its distalend portion, is inserted in the hollow cylindrical portion 151 of thedie 153, as shown in FIG. 16. Then, as shown in FIG. 17, the tubularbase member 17 is subjected to compression forming with a predeterminedpressure in the direction of the core axis, thereby forming the sealbody. By using this seal body as it is, the spherical annular sealmember 101 such as the one shown in FIG. 14 and corresponding to thespherical annular seal member 1 is obtained. Then, the inner peripheralsurface of the seal body obtained after the compression forming of thetubular base member 17 by the pressing member 162 is coated with thelubricating material by means of brushing, roller coating, spraying, orthe like. After the lubricating material thus applied is dried, theexposed surface of this coated layer is smoothed to form a coveringlayer by the truncated conical surface 102 constituted by such a smoothexposed surface, thereby making it possible to obtain the sphericalannular seal member 101 shown FIG. 14 and corresponding to the sphericalannular seal member 61.

To manufacture the spherical annular seal member 101 shown in FIG. 14and corresponding to the spherical annular seal member 71, thecovering-layer forming member 84 such as the one shown in FIG. 12referred to earlier is convoluted with the surface of its lubricatinglayer 80 placed on the inner side, thereby forming a tubular base membersimilar to the tubular base member 17. The other reinforcing sheetmember 16 made from the strip-like metal wire net such as the one shownin FIG. 3 referred to earlier is superposed on the other heat-resistantsheet member 11 containing the heat-resistant material such as the oneshown in FIG. 2 referred to earlier. This superposed assembly is woundaround an outer peripheral surface of the tubular base member 17constituted by the covering-layer forming member 84, thereby forming acylindrical preform similar to the cylindrical preform 85. In the sameway as described above, this cylindrical preform is inserted in thehollow cylindrical portion 151, i.e., over the outer peripheral surfaceof the stepped core 149 of the die 153 shown in FIG. 16, so as to befitted to the cylindrical inner wall surface 145. Then, as shown in FIG.17, the cylindrical preform is subjected to compression forming with apredetermined pressure in the direction of the core axis by the pressingmember 162 inside the die 153, as thereby obtaining the sphericalannular seal member 101.

Incidentally, in the spherical annular seal member 101, the arrangementprovided is such that the annular sliding surface of the innerperipheral surface 100 is formed by the truncated conical surface 102,and the convex spherical surface portion 138 is made to slidably abutagainst a portion of the truncated conical surface 102 at one location.Alternatively, an arrangement may be provided such that, as shown inFIG. 18, the annular sliding surface of the inner peripheral surface 100is formed by a partially concave spherical surface 171, and the convexspherical surface portion 138 is made to slidably abut against asubstantially entire area of the partially concave spherical surface171. Still alternatively, an arrangement may be provided such that, asshown in FIG. 19, the annular sliding surface of the inner peripheralsurface 100 is formed by two continuous truncated conical surfaces 172and 173, and the convex spherical surface portion 138 is made toslidably abut against the truncated conical surfaces 172 and 173partially at two locations.

Since the spherical annular seal members 101 shown in FIGS. 18 and 19are constructed in a manner similar to that for the spherical annularseal member 1, 61, or 71, it is possible to produce effects similar tothose of the above-described spherical annular seal member 1, 61, or 71.

1. A spherical annular seal member comprising: a seal body which has anannular sliding surface and in which at least a heat-resistant materialand a reinforcing member made of a metal wire have been compressed tofill meshes of the metal wire net of said reinforcing member with saidheat-resistant material such that said heat-resistant material and saidreinforcing member are integrally formed in mixed form, wherein saidreinforcing member and said heat-resistant material are respectivelycontained at a rate of 15 to 80 wt. % and at a rate of 20 to 85 wt. %,and said heat-resistant material in said seal body has a density of 1.20g/cm³ to 2.00 g/cm³.
 2. A spherical annular seal member comprising: aseal body which has an annular sliding surface and in which at least aheat-resistant material and a reinforcing member made of a metal wirehave been compressed to fill meshes of the metal wire net of saidreinforcing member with said heat-resistant material such that saidheat-resistant material and said reinforcing member are integrallyformed in mixed form; and a covering layer formed integrally with anouter peripheral surface of said seal body and formed of at least alubricating material, said annular sliding surface being formed by anexposed surface of said covering layer, wherein, in said seal body andsaid covering layer, said reinforcing member is contained at a rate of15 to 80 wt. %, and said heat-resistant material and said lubricatingmaterial are contained at a rate of 20 to 85 wt. %, and wherein saidheat-resistant material and said lubricating material in said seal bodyand said covering layer have a density of 1.20 g/cm³ to 2.00 g/cm³.
 3. Aspherical annular seal member comprising: a seal body which has anannular sliding surface and in which at least a heat-resistant materialand a reinforcing member made of a metal wire have been compressed tofill meshes of the metal wire net of said reinforcing member with saidheat-resistant material such that said heat-resistant material and saidreinforcing member are integrally formed in mixed form; and a coveringlayer formed integrally with an outer peripheral surface of said sealbody and formed such that at least a lubricating material, aheat-resistant material and a reinforcing member made of a metal wirehave been compressed to fill meshes of the metal wire net of saidreinforcing member with said lubricating material and saidheat-resistant material such that said lubricating material, saidheat-resistant material, and said reinforcing member are integrallyformed in mixed form, said annular sliding surface being formed by anexposed surface of said covering layer in which a surface constituted bysaid reinforcing member and a surface constituted by said lubricatingmaterial are present in mixed form, wherein, in said seal body and saidcovering layer, said reinforcing member is contained at a rate of 15 to80 wt. %, and said heat-resistant material and said lubricating materialare contained at a rate of 20 to 85 wt. %, and wherein saidheat-resistant material and said lubricating material in said seal bodyand said covering layer have a density of 1.20 g/cm³ to 2.00 g/cm³.
 4. Aspherical annular seal member comprising: a seal body which has anannular sliding surface and in which at least a heat-resistant materialand a reinforcing member made of a metal wire have been compressed tofill meshes of the metal wire net of said reinforcing member with saidheat-resistant material such that said heat-resistant material and saidreinforcing member are integrally formed in mixed form; and a coveringlayer formed integrally with an outer peripheral surface of said sealbody and formed such that at least a lubricating material, aheat-resistant material and a reinforcing member made of a metal wirehave been compressed to fill meshes of the metal wire net of saidreinforcing member with said lubricating material and saidheat-resistant material such that said lubricating material, saidheat-resistant material, and said reinforcing member are integrallyformed in mixed form, said annular sliding surface being formed by anexposed surface of said covering layer in which a surface constituted bysaid reinforcing member and a surface constituted by said lubricatingmaterial are present in mixed form, wherein, in an annular surface layerportion of said spherical annular seal member with a thickness of 1 mmfrom the annular sliding surface, said reinforcing member is containedat a rate of 60 to 75 wt. %, said heat-resistant material and saidlubricating material are contained at a rate of 25 to 40 wt. %, and saidreinforcing member, said heat-resistant material, and said lubricatingmaterial in said annular surface layer portion have a density of 3.00g/cm³ to 5.00 g/cm³, and wherein, in a remaining annular portion of thespherical annular seal member excluding said annular surface layerportion, said reinforcing member is contained at a rate of 20 to 70 wt.%, and said heat-resistant material is contained at a rate of 30 to 80wt. %.
 5. A spherical annular seal member comprising: a seal body whichhas an annular sliding surface and in which at least a heat-resistantmaterial and a reinforcing member made of a metal wire have beencompressed to fill meshes of the metal wire net of said reinforcingmember with said heat-resistant material such that said heat-resistantmaterial and said reinforcing member are integrally formed in mixedform; and a covering layer formed integrally with an outer peripheralsurface of said seal body and formed such that at least a lubricatingmaterial, a heat-resistant material and a reinforcing member made of ametal wire have been compressed to fill meshes of the metal wire net ofsaid reinforcing member with said lubricating material and saidheat-resistant material such that said lubricating material, saidheat-resistant material, and said reinforcing member are integrallyformed in mixed form, said annular sliding surface being formed by anexposed surface of said covering layer in which a surface constituted bysaid reinforcing member and a surface constituted by said lubricatingmaterial are present in mixed form, wherein, in said covering layer,said reinforcing member is contained at a rate of 60 to 75 wt. %, andsaid heat-resistant material and said lubricating material are containedat a rate of 25 to 40 wt. %.
 6. A spherical annular seal membercomprising: a seal body which has an annular sliding surface and inwhich at least a heat-resistant material and a reinforcing member madeof a metal wire have been compressed to fill meshes of the metal wirenet of said reinforcing member with said heat-resistant material suchthat said heat-resistant material and said reinforcing member areintegrally formed in mixed form; and a covering layer formed integrallywith an outer peripheral surface of said seal body and formed such thatat least a lubricating material, a heat-resistant material and areinforcing member made from a compressed metal wire have beencompressed to fill meshes of the metal wire net of said reinforcingmember with said lubricating material and said heat-resistant materialsuch that said lubricating material, said heat-resistant material, andsaid reinforcing member are integrally formed in mixed form, saidannular sliding surface being formed by an exposed surface of saidcovering layer in which a surface constituted by said reinforcing memberand a surface constituted by said lubricating material are present inmixed form, wherein, in said annular sliding surface, said surfaceconstituted by said reinforcing member is exposed at an area rate of 0.5to 30%, and said surface constituted by said lubricating material isexposed at an area rate of 70 to 99.5%.
 7. The spherical annular sealmember according to claim 1, wherein said heat-resistant materialcontains expanded graphite.
 8. The spherical annular seal memberaccording to claim 1, wherein said annular sliding surface includes apartially convex spherical surface, a partially concave sphericalsurface, or a truncated conical surface.
 9. The spherical annular sealmember according to claim 1, comprising an outer peripheral surfaceincluding said annular sliding surface.
 10. The spherical annular sealmember according to claim 1, comprising an inner peripheral surfaceincluding said annular sliding surface.